using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ProjectEuler6
{
    class Program
    {
        static void Main(string[] args)
        {
            var range = Enumerable.Range(1, 100);
            Func<int, int> square = x => x * x;
            Console.WriteLine(
                square(range.Sum()) - range.Sum(square)
            );
        }
    }
}

